Geological features and age constraint of basement complex in Carajás province of Brazil

The world's most important and older Archaeozoic metamorphic basement is exposed in Carajas province of Brazil, it is known as one of the metallogenic provinces that have most abundant ore deposit types and highest extent of resource aggregation. Its basement of Xingu complex is the Southern American Craton's older Archaean greenstone-gtanite body. Based on the investigation of geological features of the basement complex, the authors studied the chronology of metamorphic pluton that intruded into the metamorphic basement and put forward the understanding concerning composition, structure and tectonics of the basement complex. It is thought to be the ancient metamorphic basement with granulite-amphibolite facies gneisses and complex as the main body. The authors peeled off the charnockite and tonalite-trondhjemite granitic gneiss and further decomposed the metamorphic intrusions in different periods. The LA-ICP-MS ages of zircons in (2899±45) Ma, (2742±9.5) Ma and (2831±19) Ma were acquired in gneissic granite, and this further confirms the fact that the age of Xingu complex is Mesoarchean within 3.05-2.85 Ga, and the Xingu complex also includes two tectonic periods of supracrustal rock and gneiss suite with age of 3.05-2.96 Ga and 2.96-2.85 Ga.